1. Field of the Invention
This invention relates to a tire filling material having high resilience.
2. Description of the Prior Art
Heretofore, there have been proposed various methods or materials for avoiding the danger of puncture of tires during running. Among them, a tire filled with an elastomeric material is advantageous since it is puncture proof and control of the inner pressure is not necessary.
As tire filling materials, foamed elastomeric materials such as those disclosed in U.S. Pat. No. 3,605,848 and the like have been mainly used, but exothermicity of the materials upon running is so large that the materials are not always satisfactory. Another example of tire filling materials is polyurethane elastomer which has high resilience and thereby shows low exothermicity, but the riding comfort of a tire filled with polyurethane elastomer is poorer than that of a pneumatic tire.
Riding comfort can be improved by lowering hardness of the filling material, but when the hardness is lowered by decreasing the equivalent ratio of isocyanate groups to hydroxyl groups, the resilience is disadvantageously lowered.